1. Field of the Invention
This invention relates to a copying apparatus having an automatic document feeder. More particularly, this invention relates to a copying apparatus having an automatic document feeder including a plurality of trays for placing documents to be fed.
2. Description of the Prior Art
Various techniques are proposed in the prior art with a view to meeting demands for multijob processing in copy operation of a copying apparatus. One of the important requirements for multijob processing is to simplify handling of documents to be copied. Such a problem in handling of documents leads to how an automatic document feeder is constructed. The simpler is the construction of an automatic document feeder, the better is the function thereof. Under the circumstances, proposals have been made to provide a plurality of document inlets and/or document outlets.
Such proposals can be seen for example in U.S. Pat. No. 3,687,540 and Japanese Patent Laid-Open Gazette No. 50260/1980. U.S. Pat. No. 3,687,540 discloses a multijob copying machine comprising a plurality of trays for carrying thereon original forms and each of the trays is provided with memory means for storing the number of copies. However, it does not clearly indicate handling of a document already copied. On the other hand, according to Japanese Patent Laid-Open Gazette No. 50260/1980, there are provided a plurality of document placing tables and a plurality of document receiving tables so that copied documents fed from the document placing tables are placed on the corresponding document receiving tables. Copy conditions for a document in each document placing table are set by a button.
However, both of the above described copying machines have a construction in which the trays or tables are provided in a manner inseparable from the main body of the copying machine, which makes it difficult for users to effectively utilize such copying machines with document placing trays. More specifically, as manners of utilization of copying machines by users, there are known a distributed manner in which copying machines are provided for the respective departments of a company or the like and a centralized manner in which copying machines are utilized in a copy center commonly for the respective departments of a company or the like. In addition, the manners of utilization are also determined in view of various factors such as the number of users, the number of jobs for each user etc. An automatic document feeder is usually provided in a copying machine by option and the optimum design for an automatic document feeder is determined necessarily by the manner of utilization of the copying machine concerned. However, in such a conventional copying machine, the number of document feeding trays is fixed and accordingly it is difficult to meet the requirements of users pursuing enhancement of cost performance.